The invention relates to a method and radio station for transmitting information via a GSM mobile radio network, in which a context is defined for a traffic relationship between a mobile station and a further communications terminal via a radio interface between the mobile station and a base station.
GSM mobile radio networks were developed in order to transmit voice information to mobile communications terminals as well. The GSM mobile radio network is known, for example, from the document "Das zukunftige paneuropaische digitale Mobilfunksystem" (The future pan-European digital mobile radio system), Parts 1 to 3, H. Ochsner, Bulletin SEV/VSE (ASE/UCS), 79 (1988), dated June 4, August 6 and November 5. The mobility of communications terminals is achieved by the fact that information is transmitted via a radio interface between a mobile station (which represents one communications terminal which is involved in the traffic relationship) and a base station (which provides the network access). In the radio area of a base station, the mobile stations can be accessed all the time. Furthermore, it is known for traffic relationships to be transferred between the radio areas of different base stations. These GSM mobile radio networks can be designed as global networks, covering large areas. A context must be defined for the radio interface between the mobile station and the base station for each traffic relationship. This context comprises, for example, details about the coding to be selected, the scrambling, the encryption, the authenticity of the mobile station and of the further communications terminal as well as to the service to be selected and any other parameters.
The context definition for a traffic relationship in this case takes place while the link for this traffic relationship is being set up. It must therefore be carried out once again for each traffic relationship. For voice transmission, the time duration for context definition for each traffic relationship is not critical within the context of setting up this traffic relationship since the time consumed for context definition is short in comparison with the time duration of the voice information transmission. The use of radio resources from the radio interface for context definition is thus no longer relevant for voice links.
It is furthermore known from European Patent Specification EP 0 332 818 A2 for a mobile radio network to be adapted for data transmission. To do this, the mobile stations must be suitable for data acquisition, storage and transmission, and the mobile radio system must be able, after appropriate signaling, to carry both traffic relationships for voice information and traffic relationships for data transmission. In this case, data transmission is packet-oriented, that is to say there is no quasi-continuous information flow as in the case of voice transmission, and individual data packets are transmitted only sporadically. The relationship between the radio resources provided in the radio interface and the radio resources actually used for transmitting packetized data is unfavorable; this type of mobile radio system configuration does not allow the radio resources to be used economically.
With regard to connection control, it is possible to set up an autonomous traffic relationship for each data packet or each group of data packets, and to clear this traffic relationship down again once these packetized data have been transmitted. In consequence, radio resources are not used during the pause times and can be used for further traffic relationships. However, in this case, it has been found that the time duration for definition of the context of the traffic relationship becomes more significant in comparison with the time duration for information transmission. This means that the context definition uses a large proportion of the radio resources in comparison to that for data transmission.
It is furthermore generally known from telecommunications technology for a logic traffic relationship to be set up when a request for a traffic relationship is present, which logic traffic relationship does not continuously involve the switching resources and produces a physical traffic relationship only briefly, during the actual transmission of the wanted information. At least part of the definition of the traffic relationship context in this case takes place while the logic traffic relationship is being set up. However, there is a fixed time relationship between the definition of the context of the traffic relationship after a connection request and the setting up of this traffic relationship, and this leads to a time delay between the request for this traffic relationship and the start of the first information transmission. In this case, at the time of the request for the traffic relationship, there may also be a shortage of radio resources for the radio interface, as a result of which the setting up of the traffic relationship is further delayed, or even becomes impossible.
From EP 0 642 283 A1 it is known for a virtual channel to be set up before the transmission of packet data in a physical channel of a mobile radio network, so that the subsequent setting up of the physical channel is speeded up.